Telephone system



Sept. 12, 1944. o. A. PEARCE ET AL TELEPHONE SYSTEM Filed 001:. 15, 1942 m 4 A r A 3 A A nlu I T x x X 5 l. 9 3 s o 0 S M 5 0 :Fwoo o m Ho 00 k E o o o 0.0 ,M M IL k 0 3L r m M INVENTORS PEARCE OWEN AVIS BY SIDNEY HUGH OLIVER ATTORNEY a service.

Patented Sept. 12, 1944 ITELEPHOIJVL'E SYSTEM Owen Avis Pearce, ,Heswall', Wirral; and Sid'ney Hugh Oliver, Ainsdale, Southp'ort, near Liverpool, England, assignors, by mesne assign- I ments, to Automatic Electric Laboratories, Inc., Chicago, 111;, a corporation of'Delaware} Application October 15, 1942; Serial 'No'. 462,082

In Great Britain December l8, 194 1 11 Claims. v.-: (Cl'. 179-18) vThe present invention relates to telephonesystems and is more particularly concerned with private automatic branch exchange systems of the type provided with facilities for enabling local subscribers to gain access to a main exchange line by dialling. a special digit or exertin some other special control. The invention moreover relates to systems of this type having local'connections completed over local finder-connector links while main exchange connections, both incoming and outgoing; are completed over exchange finders having their banks multipled' to those of the local finders. Such a layout lends itself readily to the provision of arrangements 'whereby any one of a number of subscribers may answer incoming main exchange calls and also whereby main exchange calls may be transferred from one party to another. The main object of the invention is to provide improved and simplified arrangements for controlling the setting of the exchange fin'der switches:

According toone feature of the invention, a

private branch exchange telephone system having local calls set up over finder connector linkiand having main exchange calls completed'without the help of an operator over finder switches individual to the exchange lines, a circuit for starting up an exchange finder switch i adapted to be completed to a subscribers line circuit over either of two positions in the connector bank, one

of which corresponds to his-line whilethe other is characteristic of outgoing main exchange According to anotherfeature of the invention, in-a private branch exchange telephone-system having local calls set up over'finder connector links and having mainexchangecalls completed over'finder switches individual to the exchange lines, the marking'of a subscribers-line in the banks-of finders of the two types is-selectively effected over the same contact of'th'e subscribers line'relay.

A further feature vof the invention is that in 7 a private branchexchangetelephone system having'local calls setup over finder connector links and' having main exchange callscompl'et'ed without the help of an operator =over finder'switches individual to the exchangelines; the operationof a subscribers line relay is' adapted to cause a local finder'switch to connect Withthe'line whereupon the subscribers cut-ofi 're-lay i operated and the line relay is released, the-operation ofthe line relay while the cut-off relay is operated servwith the subscribers line.

'ing to cause an exchange finder toassociateitself The invention will be -better understood' from the following description ofone' met'lmd of carrying it' into effect, reference being had to the accompanying drawing in the invention is assumed to" be-applied" to ap'rivate automatic branch exchange, hereinafter abbreviated P.. A. B.X, provided with the above-mentioned facilitie$ of n ral type disclosed in British specification No. 389,867

'Ijhe 'drawing shows the circuits of -asubscribers' line; equipment; 15E? together with such parts of the circuitsof a local-link and; its associated. line finder switch LFS-"and connector switch CSand of an exchange link EL together gv lllth its" associated finder switch EFS, ass-nerves sary for understanding the underlying-principle of theinvention; The P. A. 3. X 15 assumed to normal bank (not shown) be of the single" digit type-having acapacity'ffo'r nine local subscriber's requiringthe 1 9 whilethe' digit 0 serves for mainexchange service.

The rotary switches LFS CS and Er'sme all assumed to be of the-"1 point? self interrupted drive 1st'ep-by-step type" moving always the same direction. Th'ef finder' switches LFS and. EFS have no normal positionfbut the connector switch Cs whichre'sponds to impulses isrestored to normal afternse under the controlof anaoff- Considering" now the detailed'operation, when a-local P.-Ai BJ-X subscriberremoves receiver to originate a call, thincofning negativeand po sitive conductors athe-letter"the drawingare 'loop'ed 'an dth'e line r'elay R operates. Thereupon a t-contacts r lthe cut-off 'relayfK is disconnected from the incoming xP'leadc to mark the line" as busytothe link connector switches; at contacts r2 markingbatteryvia'; resistance YA is extended over resting contact's lc l'tobank LFS5 of the local link finderswitches, and at-cont'acts r3 earth is 0 ex'tended o'ver resting contact-$165 via suitable allottin'g equipment lll to operate the start relay ST in the local linksh'own which is" assumed to be'the one allott'ed fo r use. Ther'eupon at contacts s' t'l earth-is appliedto'lead H tocomplete atdrivihgcir'cuit'for thefmagnet of theline'finder "switch BFS we at; contacts fstiia circuit is prepare'arorthe-1 test relay T; "When the finder switch wipers reach the calling line, theist' relay T operates in'series with'resistance'YAiand providesan innnediate'guard on the outlet seized finder magnet driving circuit" is open'edl'andl an operating circuitiis completed f or 'thelow r'esistance switching relay I IALin' series withthejcalling subscriberscut ofirelayK. RelayHAtheieupon at its contacts ha! and hail extends the calling line through to the local link LL, whereupon relays A and B operate and a holding circuit is completed for relay HA over contacts b2 and M3. 7

K is connected to the incoming P lead which how ever remains busied by virtue of the low resistance tacts M and k5 the markingand start circuits so-called transfer relay TR, not shown but assumed to be provided in the local link, will have been operated in this instance, on the release of relay B earth is connected over contacts hi and contacts tr of relay TR and wiper and bank CS5 and then over the J lead to operate the R relay 7 'of the called local party in addition to his K.

of the local link are opened-,'further ;points; in

these circuits being opened release of relay R.

fit-r2 and r3 on the, f 1 y I If a local extension subscriber is required, the

subscriber dials one of the digits 179.: Relay A responds and at its contacts al transmits im' pulses over lead 12 extending to the connector switch driving magnet, whereupon the wipers CSl-CSS are advanced to the required position.

Connection is effected over the connector switch -operate the;cal1in g party's line relay R... With both relays R :and K operated-the marking batterypotential is transferredto bank EFSl of the exchange finder switch EFS, while the start earth potential is extended to the exchange finder start lead l3.; Theexchange finder switch EFS "now rotates ;in search. of; the callingline ma kin a d when; r ach s q :position thetest relay' I'I operates. This brings up a switching, relay (;not shown) which serves to connect the callingline through to the battery feeding and 'impulsing relay AA, and also connects direct earth overwiperand bank EFS4 to hold relay K,-and at -the same time to shortcircuit relay HA. Relay HA thereupon releases .and opens the circuit of relay A which in turn releases relay B whereupon theconnector switch is restored to its home position'and thelocal link is freed;;for further common use. The calling linei is -now connected by :way; of v:the vexchange finder switch banks andwipersyand'the exchange link EL to the main "exchange junction line MEJ. 1 The same marking principle may also beem- -ployed to control the operation of an exchange finderunder call transfer conditions; If .a local subscriber who has been'in connection with a main exchange subscriber over an exchange finder switch and an associated exchange link desires to communicatewith a local party with the probable intention oftransferring the call, he will operate a push button provided on his telephone which in the; gmanner 7 described in British specification lion 389,867. sends a signal 7 to the exchange linkandfcauses the main exchange. connection to beheld, while access is had to. transferequi'pmentinot shown); This takes into use a local linksuch as LL over the wipers and' banks of the. associated finder switch and the-'lqcallparty then dials. the-numberof the party lto whom thecalliis to be transferre d. Y If the called local partydesires thecall to be transferred to hini,jthe calling- :loical party hangsup,

thereupon i releasing relays Aland. R. s irrtge 1 relay which will have been operated already in series with the H relay of the calling local link. 'Iheoperation of relays R and K together causes earth through the winding of relay HA. At cona-start signal tobe extended to the appropriate exchange finder switch if more than one is pro- 'vided, insubstantially the manner already de-- 'scribed and a marking corresponding to the "calledlocal line is also applied to the bank of the exchange finder switch. The wipers of this switch accordingly rotate to connect with the called local line after which it will effect the full release of the local link taken into use and also the transfer equipment. The called local party isnow left connected through to the mainexchange subscriber over switch EFS and exchange link EL. 1

. Asv regards incoming calls, these can be han dled in'several ways but no specific details are shown. One possibility is to provide an additional testing bank on the exchange finder to which marking potential is applied directly by cont'acts such as T2. .An incoming call would then effectthe ringing of a common bell and would change over relay TT tothe auxiliary testing bankwhile further contacts between com tactssuch as k5 and the allotting equipment 0 would ensure the startlclrcuit being extended to the. required exchange finder. Hence-when a party hearing the ringing of the common bell removed his receiver, the operation of relay R2 would start up the finder associated with the main exchange linein questionand mark the appropriate contact in the auxiliary bank so that the answering party would be connected through.

.An alternative arrangement wouldbe to arrange that the, relay which responded to the incoming call applied earth to the wiper such as LFS4 of the next idle local finder. Thus when a party removed his receiver to answer the in coming call, this finder would connect with his line and relay R would then be re-operated,

aregreately simplified in'comparison with Consequently earth would be connected to lead l3. and extended to the start circuit of the appro- .fpriate. finder, which on connecting with the answeringparty would release the local link by short-circuiting relay I-IA as previously described. It will thus be seen that the line equipment LE is marked on difiering finder banks according as to whether the line relay R is operated alone or in addition to the cut-01f relay K and by this means-the local line marking arrangements for use in connection with exchange finder switches the arrangements.hithertoproposed. w

The method of line marking according to the invention finds particular advantage in cases of larger capacity P. A.-B. Xs where it may be necessary to utilise switches of the two-motion type; which require'se'parate markings for the two directions of motion when used as-finders. 15 nch arrangements are shown in essencein Brit- .ish Patent No. 554,137, issued Sept. 16, 1943,

where a line relay circuit incorporating the pres- -ent invention is applied in connection with improved night service facilities on operator attended P. AsB. X boards. 3

What e Claim new and desire to secure ,by Letters Patent is:

1. In a telephone system, an exchange, subscribers lines terminating at the exchange, a

trunk line outgoing'from said exchange to another exchange, automatic switching equipment at said first exchange over whichlocal calls between said subscribers lines are completed, said equipment including a connector switch having a difierent position for each called subscribers line and having a specialposition characteristic of said trunk line, apparatus individual to each subscribers line at times operated-over said connector switch whilesarne occupies the position corresponding to that subscribers' line and at other times operated over said switch while some occupies the position characteristic of said trunk line, and a finderswitch at said first exchange terminating said trunk line and efiective responsive to the operation of said apparatus individual to any subscribers line to search for that subscribers line.

'2. In a telephone system, subscribers lines, a trunk line, a connectorswitch, wipers on said switch having different positions corresponding respectively to the different ones of said lines, means for seizingsaid switch and operating its wipers to a position corresponding to any of said lines, a finder switch terminating said trunk line and having access to all of said subscribers lines, a circuit individual to each one of said subscribers lines for starting said finder switch to hunt for that one of said subscribers lines, means for at times completing said start circuit over a wiper of said connector switch while same occupies a position corresponding to said one subscribers line and means for at other times completing said start circuit over a wiper of said connector switch while same occupies a position corresponding to said trunk line.

3. In a telephone system, subscribers lines, a trunk line, a connector switch, wipers on said switch having different positions corresponding respectively to the different ones of said lines, a finder switch efiective responsive to the intitiation of a call by any of said subscribers lines to search for and seize that line, a connection thereafter extended from the calling line over said finder switch to said connector switch, means for operating said connector switch directively over said connection thereby to move its wipers to a position corresponding to said trunk line or to any desired one of said subscribers lines, a finder switch terminating said trunk line and having access to all of said subscribers lines, a circuit individual to each one of said subscribers lines for starting said last finder switch to hunt for line relays over its associated line, a finder switch having access to all of said lines and effective upon operation of said line relay to search for the line associated with said relay, means resaid out off relay upon its operation, switching apparatus controlled over said line and said finder switch in series thereby at times to extend a connection to another one of said subscribers lines and thereby at other times to reoperate said line relay over said alternative circuit, a'trunk line, a finderswitch terminating said trunk line and having access to all of said subscribers lines, said last finder switch effective upon said reoperation of said line relay over said alternative circuit to search for the subscriber's line associated with that line relay and connect said trunk to 'said'subscribers line.

5. In a telephone system, a plurality of subscribers lines each having a line relay and a cut off relay, means for operating any of said line relays'over its associated line, a finder switch having access to all of said lines and efiective upon operation of said relay to search for the line associated with said relay, means responsive to said switch finding said line for operating the cut off relay associated therewith, thereby to restore said line relay tonormal, an alternative sponsive to said switch finding said line for operating the out off relay associated therewith, thereby to restore said line relay to normal, an alternative circuit for said line relay prepared by circuit. for said line relay prepared by said out off relay upon its operation, means for at times reoperating said line relay over said alternative circuit, and asecond finder switch having access to all of said lines efiective upon such reoperation of said line relay to search for the line associated therewith.

6. In a telephone system, a plurality of subscribers lines each having a line relay and acut off relay, means for operating any of said line relays over its associated line, a finderswitch having access to said lines and eflective responsive to such operation of a line relay to search for and seize the line associated with that relay, means for at times operating any out off relay thereby to prevent its associated line relay 'from being operated over the associated line, an alternative circuit for said line relay prepared by said out off relay upon its operation, means for operating said line relay over said alternative circuit, and a second finder switch having access to all of said lines and efiective responsive to such operation of said line relay over said alternative circuit to search for the line associated with that line relay.

'7. In a telephone system, a plurality of subscribers lines, two finder switches each having access to all of said lines, a line relay and a cut off relay for each of said lines, means for at times operating both of the relays associated with a particular line concurrently and for at other times operating each of the relays associated with that line alone, means controlled by said relays for causing one of said switches to search for said particular line whenever a parti-cular one of the relays associated with that line is operated alone and for causing the other of said switches to search for said particular line whenever both of the relays associated with that line are operated concurrently.

8. In a telephone system, a plurality of subscribers lines, two finder switches each having access to all of said lines, a line relay and a cut off relay for each of said lines, each said line having a circuit extending over a make contact on its associated cut ofi relay for causing one of said switches to start hunting for that line and a. circuit extending over a break contact on its associated cut off relay for causing the otherof said lines including the same contact on the line relay for that line.

9. In a telephone system wherein each of a plurality of subscribers lines is connected in multiple to the banks of two finder switches, andwherein each of said switches at times is operated to hunt for a marked subscribers line, a line relay and a cut oil relay individual to each subscribersline, each linealso having a vcircuit extending over a front contact of that line's cut ofi relay for at times marking said line in the bank of one of said switches and another circuit extending over a back 'contact of that lines cut off relay for at times marking said line in the bank of the other of said switches, and both of the marking circuits for each line including the same contact on the line relay for that line. r p

10. In a telephone system, a subscribers line, a line relay normally connected to said line, means for at times operating" said relay' over said line, a cut ofi'relay operated at other times to disconnect said line relay from said line, a contact on said out off relay efiective at such other times to prepare an alternative circuit for said line relay, means for operating said line relay over said alternative circuit, and. a switch efiective responsive to the operation of said line relay over said alternative circuit but not responsive to the operation of said line relay over said line for extending a connection to said line.

11. In a telephone system, a subscribers line, a line relay normally connected to said line and operable thereover, a cut ofi relay associated with said line, a numerical switch in whose bank appear a plurality of lines including said subsoribers line, means for seizing said switch and operating it to any line of said plurality, means in said switch for operating said cut oil relay when said switch is operated to said subscriber's line thereby to disconnect said line relay from said subscriber's line, a contact on said cut off relay thereupon efiective to prepare an alternative circuit for said line relay, means for at times completing said alternative circuit over said switch thereby to operate said line relay, and another switch efiective responsive to the operation of said line relay over said alternative circuit but not responsive to an operation of said line relay over said subscriber's line for extending a connection to said line.

OWEN AVIS PEARCE. SIDNEY HUGH OLIVER. 

